As with many animations in games, Resident Evil 6 allows you to prematurely "cut" a reloading animation by quickly selecting a grenade type item (grenade, remote mine, first aid spray) and then switching back to your firearm.

As an alternative, you may also attempt to press the fire button (without aiming) to perform a gun-butt with the weapon, which also "completes" the magazine reload, but places your character in the gun butt animation. This, and other actions (taking cover, diving, etc.) may be faster or slower than weapon switching, but will depend on the situation you are in (esp. the very fluid situations in Mercenaries Mode).You can also try switching aiming side from left to right when the character has already put the magazine on the weapon you hit the R3(right analog stick) and it will switch aiming side and cutting the reloading animation.

This animation exploit allows you to cut down the animation cool-down periods for certain weapons (notably the grenade launcher), letting you fire the weapon a few moments earlier. This exploit does not apply to weapons with manually worked actions, such as the six-shot "Sniper Rifle", the regular shotgun, Piers' Anti-Material Rifle, etc.

Skill points can be time-consuming to get large amounts of for the most expensive skills, but certain areas allow you to collect more in short order:

You can always go to Chapter 2 in Leon's campaign and fight all the Shriekers(1k pts), Bloodshots(1k pts) and the Bloodshots (100 - 500 pts) at the Cathedral.

Chapter 3 of Jake's helps a bit with the new looking C-type "el gigante" from who we know from RE4. They drop 4k points a piece.

Play Mercenaries. Since dealing with "Urban Chaos" will be mostly what you have to start with til you beat the game. You get plenty of kills, ammo, and Bigger infect like Bloodshots and Whoppers(Big Fat zombies that take a lot of damage)

Chapter 4 of Leon(this needs to be done in co-op) the part that you need to beat Chris to the elevator... if you beat him you'll find 2 treasure boxes with 2,000 skill point in each box... now enter the room 01... when you start to hack the locks you need to do it fast because if you dont chris will beat you to it and you will lose 14,000 skill points... so when you open the door you'll find 3 boxes in the next area, grab'em when you do ask your partner to leave the game(doesn't matter wich one it is as long the one that leaves has the chapter saved and can invite you back to the checkpoint before the elevator)then after he/she leaves keep playing until you reach the Simmons cutscene, skip it, wait for game to save, quit and repeat.